Tennis string or like article



Feb. 25, 1958 F. J, GREGORY 2 TENNIS STRING OR LIKE ARTICLE 7 Filed novzo, 195s INVENTOR. flex/7 115 f re gory flwymzw ATTORNEYS.

United States Patent i This invention relates to a tennis string or likearticle. Rackets which are used for tennis, badminton, squash, and soforth, are formed by a frame across which there extend strings ingenerally right angular relationship to provide a mesh surface whichwill have more or less resiliency depending upon the character of thestrings used.

2 ,824,435 Patented Feb. 25, '1958 more or less solid string in whichthe multi-filament core will remain firmly in place even at the point ofsharp bending. With reference to the drawings, designates generally abraiding machine shown diagrammatically, there being provided a bed 11in which is provided the serpentine raceway for the braider carriers 12which carry a single mono-filament nylon strand 13, which, as shown,extends to the former 14, which controls diameter and strips otf excessliquid nylon, where it is braided about a multifilament'nylon strand 15which is passed through a liquid bath 16 of nylon in a volatile solventhaving been drawn from the package 17 over a guide roller 18 beneath theimmersing roller 19 and through a pair of nip and feeding rollers 20.

The multi-filament core is shown on a somewhat enlarged scale in Figure4,. there being there shown a plurality of these filaments 21 which goto make up the core and interspersed between these filaments is nylon 22which Originally such strings were formed of catgut, but because of theeffect that moisture may have upon this material, it is desirable toform the string of some synthetic material which will be less affectedby moisture.

One of the objects of this invention is to provide a more solid stringthan has heretofore been formed of synthetic material.

Another object of the invention is to provide a string which may bedrawn tighter and therefore provide a faster ball when struck with aracket having such strings.

Another object of the invention is to reduce the sliding of one stringupon the other and therefore improve wearing qualities of the stringswhich are used in a racket of :this character.

Another object of the invention is to provide a string which willmaintain the form in which it is first furnished tthroughout the life ofthe racket.

With these and other objects in view, the invention consists of certainnovel features of construction and steps in manufacture as will be morefully described and particularly pointed out in the appended claims.

In the accompanying drawings:

Figure 1 is a diagrammatic view illustrating the braiding of a coverover a core;

Figure 2 is a diagrammatic view illustrating a subsequent operation onthe string after formed as shown in Figure 1;

Figure 3 is a plan view of a string on large scale showing the braidedcovering thereon and the core therein;

Figure 4 is a greatly enlarged sectional view showing the multi-filamentcore and the mono-filament braided cover about the core with the wholeimpregnated with some material such as nylon.

A strand of nylon as it appeared on the market some time ago was made upof a large number of filaments of small diameter arranged in generallyaxially parallel relation. More recently a strand of nylon has beensupplied to the market of a solid form in cross section and in adiameter which may be used without plying it with other strands. Thislatter form is many times the diameter of any one of the singlefilaments of the earlier form. To distinguish these two forms the traderefers to the earlier form as a multi-filament strand and the latterform as a mono-filament strand, and I here use the terms with suchdistinction as is used in the trade.

In proceeding with this invention, I pass a multi-filament strand ofnylon filaments through a solution of liquid nylon and braid about thiscore before the liquid nylon becomes set up or hard, a covering of nylonmonofilaments and then reel the same, and after so formed,

the entire strand may be again dipped in liquid nylon becomesimpregnated in the core 15 as a liquid from the bath 16 andthereafterbecomes hardened as its solvent evaporates tofill in'thespaces between the multi-filaments and provide a generally solid mass.

The mono-filaments 13 are shown as about the core 15, there being hereillustrated eight of such mono-filaments as formed on an eight-carrierbraider for the particular form of line which is here illustrated,although any braider where the carriers are in multiples of four may beused. Each of these mono-filaments 13 is many times the diameter of oneof the multi-filaments 21. The covered strand is drawn through themachine through feeding rolls 25 and packaged as at 26. Some of theliquid bath 16 oozes through the mono'filament cover to provide acoating on the outer surface of the cover.

This package 26 is then further treated by drawing the covered strand 27thereof through a second liquid bath 28 of nylon dissolved in a volatilesolvent in the trough 29 by passing the line over rolls 30, 31 andbeneath the immersing roll 32, after which the string 33 is then driedat some heat usually somewhat above room temperature in order toaccelerate the evaporation of the nylon solvent. I have illustrated oven34 into which the string may pass and be disposed back and forth overguides 35 and 36 to increase its extent in this heating device, afterwhich it is packaged in finished form as at 37. This second treatmentthrough the nylon bath serves to fill in the spaces between themono-filaments as at 38, although the liquid on the multi-filament corewill provide an outer covering as the mono-filaments are braided aboutit.

The tennis string may be used as it comes from the braider as shown inFigure 1 without the immersion as shown in Figure 2. However, the secondbath does provide a smoother string in that the interstices of the braidare better filled by this second bath, although the diameter of thestring is scarcely increased by the treatment.

By the above steps I provide an article which has improved wearingqualities and in which the multi-filament core will not pop out throughthe mono-filament cover upon sharp bending or upon the ball being struckwith a racket strung with string of this structure. There is also asuflicient roughness to the string so that when the ball .is hit, it maybe cut to spin the same as is desirable.

I claim:

1. A tennis string comprising a multi-filament core with a braided coverof mono-filament strands, said core and cover having similar chemicaland physical characteristics and said mono-filaments each being manytimes the diameter of each of the multi-filaments.

2. A tennis string comprising a multi-filament core with a braided coverof mono-filament strands, said string being impregnated with material tofill the interstices thereof, ,said core, cover, and, material havingsimilar chemical and physical characteristics and said monofilamentseach being many times the diameter of each of the multi-filaments;

3. A tennis string comprisinga multi filament core of nylon with abraided cover of mono-filament strands, of nylon, said mono-filamentbeing many timesth'ediameter of each of the multi-filaments.

4. A tennis string comprising a multi-filament core with a braided coverof mono-filament strands, the core of said string being impregnated withmaterial to fill the interstices thereof, said core, cover and materialhaving similar chemical and physical characteristics and saidmono-filaments each being many times the diameter of each of themulti-filaments.

-5. A tennis string comprising a multi-filament core with a braidedcover of mono-filament strands, the core and cover of said string beingimpregnated with material to fill the interstices thereof, said core,cover and materiil having similar chemical and physical characteristicsand said mono-filaments each being many times the diameter of each ofthe multi-filaments.

6. The method of forming a tennis string which comprises braiding amono-filament cover over a multi-filament core which has just beenimmersed in an adherent bath and is still soft and plastic, said cover,core and bath having similar physical and chemical properties, said.mono-filament being many times the diameter of each of themulti-filaments.

7. The method of forming a tennis string which comprises braiding anylon mono-filament cover over a nylon multi-filament core which hasjust been immersed in an adherent bath of nylon and is still soft andplastic said mono-filament being many times the diameter of each of themulti-filaments.

8. The method of forming a tennis string which comprises braiding anylon mono-filament cover over a nylon multi-filament core which hasjust been immersed in an adherent bath of nylon and is still soft andplastic and then passing the whole through abath of liquid nylon anddrying the same said mono-filament being many times the diameter of eachof the multi-filaments.

References Cited in the file of this patent UNITED STATES PATENTS2,257,648 Pierce Sept. 30, 1941 2,590,586 Thompson et al Mar. 25, 19522,649,833 Crandall Aug. 25, 1953 2,712,263 Crandall a, July 5, 1955FOREIGN PATENTS 674,383 Great Britain June 25, 1952

